How can I make the animation to be loop without starting from the first frame but from the last frame?
Your question is not clear, do you want the object to come back to the center or do you want it to continue further to the left after frame 120 ?
For the first case, see Vklidu's answer.
If you want the object to continue further and indefinitely to the left, go in the Dopesheet press ShiftE &gt; Linear Extrapolation (or Channel menu &gt; Extrapolation mode &gt; Linear Extrapolation)